1. Field of the Invention
The present invention relates to a rolling bearing for use in automobile fuel jet controller, particularly apparatus for controlling the speed or idle rotation, exhaust gas recycling apparatus, electronic throttle controller, etc. More particularly, the present invention relates to a rolling bearing for fuel jet controller having improved low temperature torque properties and high temperature durability.
2. Description of the Related Art
Rolling bearings for use in automobile fuel jet controller such as apparatus for controlling the speed of idle rotation, exhaust gas recycling apparatus and electronic throttle controller are often required to exhibit a good durability at high temperatures and good torque properties at low temperatures. To this end, high temperature durability or low temperature torque properties have been heretofore attained by filling a lithium soap-ester oil-based grease or urea-synthetic hydrocarbon oil-based grease in the rolling bearing as a lubricant which uses a synthetic oil as a base oil. Low temperature torque properties, if particularly demanded, have been attained by the use of a lubricant such as ester oil and fluorine-based oil.
In recent years, however, the requirements for the performance of rolling bearings for use in these fuel jet controllers have been severer. For example, an exhaust gas recycling apparatus is intended to recycle exhaust gas which has been just emitted to further reduce the amount of NOx in the engine exhaust gas. Thus, the rolling bearing used in the exhaust gas recycling apparatus is exposed to temperatures as high as close to 200.degree. C. Accordingly, lubricants which have heretofore been filled in these apparatus such as lithium soap-ester oil-based grease, urea-synthetic hydrocarbon-based grease, ester oil and fluorine-based oil cannot maintain high temperature durability.
As mentioned above, the grease or lubricant filled in the conventional rolling bearings for use in automobile fuel jet controller, particularly apparatus for controlling the speed or idle rotation, exhaust gas recycling apparatus, electronic throttle controller, etc. exhibits a limited high temperature durability while satisfying its desired low temperature torque properties. Thus, the conventional grease or lubricant cannot exhibit further improvement in high temperature durability. Further improvement has been desired in low temperature torque properties.